Indocyanine green-based adjunctive antimicrobial photodynamic therapy for treating chronic periodontitis: A randomized clinical trial.

BACKGROUND: The objective was to evaluate the efficiency of indocyanine green (ICG)-based adjunctive antimicrobial photodynamic therapy (aPDT) in a prospective clinical study regarding non-surgical treatment of chronic periodontitis. METHODS: Affected teeth of twenty patients were treated with scaling and root planing (control group). Using a split-mouth design, two quadrants received additional ICG-based (perio green®, 0.1 mg/ml) aPDT (test group) with a diode laser at 808 nm (100 mW at 2 kHz). Clinical assessment of bleeding on probing (BOP), sulcus fluid flow rate (SFFR) and microbiological analysis were performed at baseline, two weeks, three and six months after treatment. Relative attachment level (RAL), probing depths (PD) and gingival recession (GR), were also analyzed. RESULTS: At baseline, none of the assessed parameters showed significant differences between the test and control groups. Median values for BOP, RAL, PD, decreased significantly in both groups after three months of treatment (p ≤ 0.05) without significant difference between the groups. Two weeks after treatment, the SFFR showed significantly lower mean values in the test group (aPDT). CONCLUSION: Within the study limits, the only significant difference between the control group and the aPDT group was a transient smaller amount of SFFR in the latter during the first follow-up. With the applied parameters, this study does not conclusively support ICG-based aPDT, though it is promising because no adverse effects occurred. The precise modes of action of ICG must be elucidated, and further clinical trials are needed.

Ablation of carious dental tissue using an ultrashort pulsed laser (USPL) system.

The aim of the study was to investigate the efficiency of caries removal employing an ultrashort pulsed laser (USPL) and to compare the results regarding to the ablation rate of sound enamel and dentin including surface texture. The study was performed with 59 freshly extracted carious human teeth. Two cavities with an edge length of 1 × 1 mm per tooth were created: one in the dental decay and one in sound hard tissue. For this purpose a 9-W Nd:YVO4 laser with a center wavelength of 1,064 nm and a pulse duration of 8 ps at a repetition rate of 500 kHz was used. A scanner system moved the laser beam across the surface with a scan speed of 2,000 mm/s. Ablated volume and roughness R z of the cavity ground were measured using an optical profilometer. Subsequently, the specimens were cut to undecalcified sections for histological investigations. The removal of dental decay (dentin, 14.9 mm(3)/min; enamel, 12.8 mm(3)/min) was significantly higher (p < 0.05) compared to the removal of sound tissues (dentin, 4.2 mm(3)/min; enamel, 3.8 mm(3)/min). The arithmetic means of the surface roughness R z were 8.5 µm in carious enamel, 15.43 µm in carious dentin, 4.83 µm in sound enamel and 5.52 µm in sound dentin. Light microscopic investigations did not indicate any side effects in the surrounding tissues. Regarding the ablation rate of dental decay using the USPL system, caries removal seems to be much more efficient for cavity preparation.

Ultrashort pulsed laser (USPL) application in dentistry: basic investigations of ablation rates and thresholds on oral hard tissue and restorative materials.

Modern ultrashort pulse lasers with scanning systems provide a huge set of parameters affecting the suitability for dental applications. The present study investigates thresholds and ablation rates of oral hard tissues and restorative materials with a view towards a clinical application system. The functional system consists of a 10 W Nd:YVO4 laser emitting pulses with a duration of 8 ps at 1,064 nm. Measurements were performed on dentin, enamel, ceramic, composite, and mammoth ivory at a repetition rate of 500 kHz. By employing a scanning system, square-shaped cavities with an edge length of 1 mm were created. Ablation threshold and rate measurements were assessed by variation of the applied fluence. Examinations were carried out employing a scanning electron microscope and optical profilometer. Irradiation time was recorded by the scanner software in order to calculate the overall ablated volume per time. First high power ablation rate measurements were performed employing a laser source with up to 50 W. Threshold values in the range of 0.45 J/cm(2) (composite) to 1.54 J/cm(2) (enamel) were observed. Differences between any two materials are statistically significant (p < 0.05). Preparation speeds up to 37.53 mm(3)/min (composite) were achieved with the 10 W laser source and differed statistically significant for any two materials (p < 0.05) with the exception of dentin and mammoth ivory (p > 0.05). By employing the 50 W laser source, increased rates up to ∼50 mm(3)/min for dentin were obtained. The results indicate that modern USPL systems provide sufficient ablation rates to be seen as a promising technology for dental applications.

Heat generation caused by ablation of restorative materials with an ultrashort pulse laser (USPL) system.

Heat generation during the removal of dental restorative materials may lead to a temperature increase and cause painful sensations or damage dental tissues. The aim of this study was to assess heat generation in dental restoration materials following laser ablation using an ultrashort pulse laser (USPL) system. A total of 225 specimens of phosphate cement (PC), ceramic (CE), and composite (C) were used, evaluating a thickness of 1 to 5 mm each. Ablation was performed with an Nd:YVO(4) laser at 1,064 nm, a pulse length of 8 ps, and a repetition rate of 500 kHz with a power of 6 W. Employing a scanner system, rectangular cavities of 1.5-mm edge length were generated. A temperature sensor was placed at the back of the specimens to record the temperature during the ablation process. All measurements were made employing a heat-conductive paste without any additional cooling or spray. Heat generation during laser ablation depended on the thickness of the restoration material (p < 0.05) with the highest values in the composite group (p < 0.05), showing an increase of up to 17 K. A time delay for temperature increase during the ablation process depending on the material thickness was observed in the PC and C group (p < 0.05) with highest values for cement (p < 0.05). Employing the USPL system for removal of restorative materials, heat generation has to be considered. Especially during laser ablation next to pulpal tissues, painful sensations might occur.

Short-term clinical effects of adjunctive antimicrobial photodynamic therapy in periodontal treatment: a randomized clinical trial.

OBJECTIVE: The aim of this study was to assess the effect of adjunctive antimicrobial photodynamic therapy (aPDT) in chronic periodontitis. MATERIAL AND METHODS: Twenty patients with untreated chronic periodontitis were included. All teeth received periodontal treatment comprising scaling and root planing. Using a split-mouth design, two quadrants (test group) were additionally treated with aPDT. Sulcus fluid flow rate (SFFR) and bleeding on probing (BOP) were assessed at baseline, 1 week and 3 months after treatment. Relative attachment level (RAL), probing depths (PDs) and gingival recession (GR) were evaluated at baseline and 3 months after treatment. RESULTS: Baseline median values for PD, GR and RAL were not different in the test group and control group. Values for RAL, PD, SFFR and BOP decreased significantly 3 months after treatment in the control group (median delta RAL: -0.35 mm, inter-quartile range: 0.21 mm), with a higher impact on the sites treated with adjunctive aPDT (median delta RAL: -0.67 mm, inter-quartile range: 0.36 mm, p<0.05). GR increased 3 months after treatment with and without adjunctive aPDT (p<0.05), with no difference between the groups (p>0.05). CONCLUSIONS: In patients with chronic periodontitis, clinical outcomes of conventional subgingival debridement can be improved by adjunctive aPDT.